Ecclesiology means the doctrine of the church, her being, ministry, mission, and worship. The sacraments, such as water baptism and the Eucharist, are practices and doctrines of Catholic ecclesiology. Theologically, therefore, ecclesiology is the study of the Church, the origins of Christianity, its relationship to Jesus (bride and groom), its role in salvation, its polity, its discipline, its eschatology, and its leadership.

 

DOGMATIC CONSTITUTION ON THE CHURCH
LUMEN GENTIUM
SOLEMNLY PROMULGATED BY HIS HOLINESS
POPE PAUL VI
ON NOVEMBER 21, 1964

 

https://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19641121_lumen-gentium_en.html